yes there is a difference in using a hoop vs without. However, both are acceptable and show good results.
Using a hoop or fram gends to be a bit more flatter than without. However both are ok if get the results you want.
A large quilt tends to become cumbersome if quilting without a hoop or frame.
I really prefer the No Slip Hoop - can get them at JoAnns. Largest is 14" which works for all sizes. It is about $20.
But, when set in hoop it does not slip. I use it in all my classes and even seasoned quilters rave about it.
I can never get the quilt to be the tightness/looseness I want with the Q-Snap.